1. Field of the Invention
The present invention relates to a spread spectrum clock generator, and in particular relates to an all-digital spread spectrum clock generator.
2. Description of the Related Art
Serial Advanced Technology Attachment (SATA) is widely used in internal storage interconnection for giga-bit-per-second data rate operating at high data rates; the high-frequency clock causes electromagnetic interference (EMI) which may affect the wireless communication systems. Accordingly, there are several techniques which have been presented to suppress the EMI, such as a frequency modulation (FM), pulse swallow technique, phase interpolation, digital delay line modulation, and delta-sigma modulation. Among these techniques, the delta-sigma modulation based fractional-N frequency synthesizer is becoming a popular one, because it is almost digitally realized and has a better EMI reduction performance.